Eastern Roman emperor from 450 to 457, the last ruler of the dynasty begun by the emperor Theodosius I (died 395). His relatively peaceful reign, which was later viewed as a golden age in the Eastern Roman Empire, provided a marked contrast to the violence that was destroying the Western Empire.

Beginning his career as a professional soldier, Marcian came to hold a high position in the service of Aspar (Aspar, Flavius Ardaburius), Theodosius II's powerful master of soldiers. After Theodosius' death in 450, Aspar and Theodosius' sister, Pulcheria, had Marcian appointed emperor (August 25). As part of this arrangement, Marcian was made the nominal husband of Pulcheria in order to formally perpetuate the Theodosian dynasty.

Marcian was an able administrator who left a well-filled treasury upon his death. He saved money by refusing to pay the annual tribute to the Huns and by carefully avoiding costly military ventures abroad. There were minor troubles with nomadic peoples in Syria and along the frontier of southern Egypt, but he refused to become entangled in war with the Vandals in Africa. The most notable event of his reign was the fourth ecumenical council assembled by Marcian at Chalcedon (Chalcedon, Council of) (modern Kadıköy, Tur.) in 451. This council upheld the orthodox Christian doctrine that Christ had two natures, divine and human, and rejected Monophysitism, which maintained that Christ had one divine nature. Marcian's daughter Euphemia was married to Anthemius, emperor of the West from 467 to 472. Leo I became emperor of the Eastern Empire upon Marcian's death.